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Solar Installations on Closed Landfills: Technical and

Regulatory ConsiderationsGabriel Sampson

EPA OSRTI NNEMS Fellow

Bren School of Environmental Science and ManagementUniversity of California, Santa Barbara

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Goal

• Summarize the findings from 2009 research, including the following:

1. The opportunity for solar energy on landfills

2. Relevant solar power system technologies

3. Technical challenges

4. Regulatory complications

5. Case evidence

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Problem Statement

• Thousands of closed landfills across US1

• EPA OSWER OCPA currently encouraging placement of clean energy on contaminated lands

• Recurring challenges:– Technical (e.g. cap integrity and site remedy)– Regulatory (state and local)

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Solar Power Systems

• Ground mounted system components– Stanchions– Footings

• Shallow concrete pillars;• Slab;• Ballasted frames;• Driven pile

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Solar Power Systems

Retrieved from flickr.com

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Solar Technologies

• Photovoltaic– Panels

1. Thin film/amorphous

2. Polycrystalline

3. Monocrystalline

– Mounting structures1. Fixed tilt

2. Single axis tracker

3. Double axis tracker

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Solar Technologies

• Concentrating Solar Power (CSP)1. Linear concentrators

1. Parabolic trough

2. Fresnel reflector

2. Power towers

3. Dish/Engine Systems

Large scale2 production

Small scale production

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Weight Considerations

• PV panel weight– Thin film

• Generally light weight• Flexible• Less efficient per unit area

– Crystalline• Heavier• Rigid• More efficient (monocrystalline > polycrystalline)

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Table 1 – Weight specifications for various solar PV panels. www.wholesalesolar.com

P=polycrystalline, M=monocrystalline, A=amorphous thin film

Weight Considerations

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Weight Considerations

Courtesy of Tony Walker, Republic Services, twalker@republicservices.com

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PV Weight Considerations

• System mounting1. Single and double axis sun trackers

2. Fixed tilt

• Foundations1. Ballasted platform;

2. Concrete footings (poured and pre-fabricated);

3. Slab

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Wind and Snow Loading

• IEC standards ~ 50 pounds per square foot mechanical loading (wind speed of ~105 mph)

• Consider how wind loading is impacted by operations and maintenance activities

• Snow loading and side slope stability

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Technical Challenges:Landfill Settlement

• Processes1. Biochemical degradation;2. Physiochemical changes;3. Raveling;4. Any combination of 1-43

• Dependent on waste 1. Age;2. Depth;3. Type;4. Method of placement

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Technical Challenges:Landfill Settlement

• Differential settlement– Impacts on site remedy

1. Surface cracks;2. Water drainage system;3. Leachate and gas piping;4. Surface depressions;5. Underground utilities

– Impacts on solar system structures1. Piers and footings;2. Aspect of solar panels

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Technical Challenges:Landfill Settlement

• When settlement is a concern1. Tracking vs. fixed mounting structures

2. Foundation materials

3. Weight of solar array

• Mitigation1. Simultaneous closure and development

2. Previously closed landfills

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Technical Challenges:Cover Material Integrity

• Clearing and grading activities

• Cover thickness and risk to cap performance

1. Redistribute or import new soil

2. Support foundation

3. Trenching for electrical lines

• Regulatory restrictions

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Technical Challenges:Slide Slope Stability

• Slope instability generally decreases with time4

• Constructing on steep slopes1. Increased erosion and stormwater control

2. Increased O&M costs

3. Foundation considerations

• Snow and ice loading

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Technical Challenges:Future Site Remedy Management

• Consider1. Settlement surveys;

2. Landfill gas surveys;

3. Gas extraction activities;

4. Erosion inspections;

5. Cap maintenance

• Access roads

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Technical Challenges:Review

Complication Challenges Potential Remedy Example Steep side slope

Anchoring solar panels

Stormwater Erosion Snow & wind

loading

Flexible PV laminates Other light weight solar

system that provides secure foundations

Re-grading and soil amendments

Tessman Road Landfill case study

Thin landfill cap cover

Puncturing landfill cap

Light weight, non-invasive foundations

Ballasted solar platforms and shallow footings

Fort Carson Army Base case study

Settlement Depressions Infiltration System foundations Gas and leachate

piping Underground utilities

Fixed tilt mounting structures

Light weight shallow footings and ballast

Pre-closure mitigation Geogrid reinforcement Selective placement (older

waste, construction and demolition waste)

Pennsauken Landfill, Holmes Road Landfill

Wind and snow loading

System connections Foundation stability

Use solar panels and mounting structures with high mechanical load rating

Avoid side slope placement

Not available

Routine cap maintenance

Settlement surveys Gas extraction

activities Erosion inspections Vegetation

management

Plan solar array placement around monitoring well heads

Design panel height to allow for routine landscaping practices

Existing permanent access roads

Not available

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Regulatory Complications:Permitting

• RCRA Subtitle D

• State and local government responsible

• 2008 survey5

– 13 states responded– No ordinances against landfill development

• Permitted closure?

• Alternative cover design

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Regulatory Complications:Permitting

Roberts, M., Perera, K., Alexander, T., Walker, T. “Alternative Landfill Closure: Solar Energy Cover System.” 2008. Engineering design paper provided by Tony Walker, Republic Services, twalker@republicservices.com

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Regulatory ComplicationsPermitting

• Solid waste site assignment;• Landfill property deed;• Environmental site assessment;• Closure permit and certification;• Site plan;• Landfill capping design plan;• Post-closure use design plan;• Storm waster drainage/Run-off

control plan;• Storm water erosion control

plan;• Landfill gas control and

monitoring plan;

• Geotechnical stability and settlement analysis;

• Capping system interface;• Utilities description;• Environmental monitoring

description;• Qualitative health and

environmental risk assessment;• Post-closure monitoring and

maintenance plan;• Financial assurance;• Wetlands protection plan;• Documentation that the site is in

compliance with state environmental protection statutes6

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Regulatory Complications: Zoning and Land Use

• Refer to local government ordinances

• Notify local planning department and enforcement agencies

• e.g. Minnesota– MPCA owns 25 of 112 landfills under CLP– MPCA has right to limit land use on all sites7

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Regulatory Complications:Environmental Site Investigations

• Environmental site investigation– Previously conducted ESI– Refer to local regulator

• Confirm location of well heads– Plan placement accordingly

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Regulatory ComplicationsLiability

• CERCLA

• Brownfields Law

• EPA tools

• State liability protection

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Regulatory ComplicationsLiability

State Liability Protection Massachusetts Parties that complete a site cleanup have liability protection against

Commonwealth claims for response action and natural resource damage costs once cleanup is complete.

Michigan The Michigan Natural Resources and Environmental Protection Act of 1994 exempts landowners from liability for contamination if they perform an environmental investigation and submit it to state authorities within 45 days of purchasing the land.

New Jersey New Jersey offers limited covenants not to sue, innocent land purchaser defenses, and Prospective Purchaser Agreements.

Oregon Oregon offers a Prospective Purchaser Agreement. Pennsylvania Parties may be excluded from liability for state approved cleanups. Wisconsin The Wisconsin Remediation and Redevelopment program consolidates many

state and federal programs into a single program to assist in the redevelopment of contaminated lands. Certain parties may be found to have limited liability through the state’s Voluntary Party Liability Exemption.

National Association of Local Government Environmental Professionals, Northeast-Midwest Institute. “

Unlocking Brownfields: Keys to Community Revitalization.” Retrieved online from http://www.resourcesaver.com/file/toolmanager/CustomO93C337F65023.pdf on August 4, 2009.

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Case Evidence:Fort Carson

• Site Name: Fort Carson, SWMU 9• Location: Fort Carson, CO, Region 8• Site Type: Construction debris landfill• Size: 2 megawatt • Panels: First Solar FS-272 72.5 watt amorphous thin film• Inverters: 500 kilowatt SATCON, 408 volts DC power to 200 volt AC, 2400

amps • Transformers: 500 kilovolt-amps 200 volts/12,470 volts • Footings: 30” wide x 30” deep, 120” long, 6” above grade, 24” below grade,

24’ on center spacing, anchor bolts for front and rear stanchions;• Stanchions: 4” 60 gauge steel, 101” height in rear, 25” height in front;• Beams and supports: 12 gauge steel C-channels, 287” long, 10” deep,

slots cut into beams to allow for side-to-side adjustment, rails are 16 gauge z-channels, rails support module clips and are secured to the beams in front and rear.

• Vince Guthrie, Utility Programs, Fort Carson, Vincent.guthrie@us.army.mil

28Retrieved from flickr.com

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Retrieved from flickr.com

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Case Evidence:Holmes Road Landfill

• Site Name: Holmes Road Landfill• Location: Houston, TX, Region 6• Site Type: Municipal solid waste landfill• Size: 10 megawatt (projected)• Status: Under review• Fixed tilt single axis mounting structures;• Poured concrete footings;• Amorphous thin film solar photovoltaic panels;• 500 kilowatt inverters;• 21,740 AMAT line. Rob Lawrence, Senior Policy Advisor, US EPA Region 6,

Lawrence.rob@epa.gov, 214-665-6580 SRA International. “Solar Power Analysis and Design Specifications:

Technical Assistance to the City of Houston.” Retrieved online from http://www.epa.gov/brownfields/sustain_plts/factsheets/houston_solar.pdf on July 30, 2009.

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Case Evidence:Nellis Air Force Base

• Site Name: Nellis Air Force Base• Location: Nellis Air Force Base, NV, Region 9• Site Type: Municipal solid waste landfill• Size: 14.2 megawatts• Panels: 72, 416 - SunPower Corporation, SANYO, SunTech Power Holdings, and

Evergreen Solar, Inc. crystalline panels.• Mounting Structure: 5,821 - SunPower T20 and SunPower Tracker single axis sun

tracking systems;• Foundation: Concrete footing foundations;• Inverter: 54 - Xantrex Technology, Inc.• Nellis Air Force Base Internal and Media Relations, 702-652-2407• SunPower. “Nellis Air Force Base Case Study Fact Sheet.” Retrieved from

http://us.sunpowercorp.com/business/success-stories/success-story-pdfs/federal-government/SPWRNellis_CS.pdf on August 4, 2009.

• Nellis Air Force Base. “Nellis Air Force Base Solar Power System Fact Sheet.” Retrieved from http://www.nellis.af.mil/shared/media/document/AFD-080117-043.pdf on August 6, 2009.

32Retrieved from flickr.com

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Case Evidence:Tessman Road Landfill

• Site Name: Tessman Road Landfill• Location: San Antonio, TX• Site Type: Municipal Solid Waste Landfill• Size: 182 megawatt hours• Geomembrane: Firestone 60 millimeter thermoplastic polyolefin.• Panels: 1,050 Uni-Solar photovoltaic laminates (PVL) flexible panels

positioned parallel to the landfill grade. Dimension for the panels is 15.5”x216”x0.25”.

• Adhesive: SikaLastomer-68 ethylene propylene copolymer.• Tony Walker, Republic Services, 480-627-7088• Solar Cap Project. Republic Services, Inc. 2008. Retrieved from

http://www.fhsanantonio.com/video/republic/ on August 10, 2009.• Roberts, M., Perera, K., Alexander, T., Walker, T. “Alternative Landfill

Closure: Solar Energy Cover System.” 2008. Engineering design paper provided by Tony Walker, Republic Services, twalker@republicservices.com

34Photo courtesy of Tony Walker,

Republic Services

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Case Evidence:Pennsauken, NJ

• Site Name: Pennsauken Landfill• Location: Pennsauken, NJ• Site Type: Municipal Solid Waste Landfill• Size: 2.1 megawatt• Panels: Crystalline photovoltaic;• Mounting Structures (top deck): Concrete ballasted; • Mounting Structures (side slop): Pre-cast concrete footings.• Mark Messics, P.E., Senior Business Development Manager, PPL

Renewable Energy, mcmessics@pplweb.com• Messics, Mark. “Case Study: Pennsauken Landfill Solar Project.”

Presented at Renewable Energy at Closed Landfill Workshop. Mansfield/Foxboro Holiday Inn, Mansfield, MA. June 17, 2009. Retrieved from http://www.mass.gov/dep/energy/pennsauk.pdf on August 13, 2009.

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Conclusions

• New and developing practice

• A number of benefits

• Recurring challenges

• Engineering measures available

• Complicated regulatory context

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References1Suflita, J.M., Gerba, C.P., Ham, R.K., Palmisano, A.C., Rathje, W.L., Robinson, J.A. “The World’s Largest Landfill: A

Multidisciplinary Investigation. Environmental Science and Technology 26.8 (1992): 1486-1495. 2Stoddard, L., Abiecunas, J., O’Connel, R. “Economic, Energy, and Environmental Benefits of Concentrating Solar

Power in California.” NREL/SR-550-39291. Golden, CO: National Renewable Energy Laboratory, 2006. Available online at http://www.nrel.gov/csp/pdfs/39291.pdf.

3Christensen, T.H., Cossu, R., Stegmann, R. Landfilling of Waste: Barriers. London: E & FN Spon, 1994. Electronic. 4Misgav, A., Perl, N., Avnimelech, Y. “Selecting a Compatible Open Space Use for a Closed Landfill Site.” Landscape

and Urban Planning 55.2 (2001): 95-111. Electronic. 5Masson, P.T. 2008. “Should Landfills be Redeveloped: What do Various States Think?” Presented at 2008 Solid

Waste Association of North America – 23rd Annual Northwest Regional Solid Waste Symposium. McMenamins Edgefield, Troutdale, OR. April 17, 2008. Retrieved from http://www.swanaoregon.org/symposium_2008.htm on July 21, 2009.

6Massachusetts Department of Environmental Protection. 2009. “Landfill Post-Closure Use Permitting Guidelines.” Retrieved from http://www.mass.gov/dep/recycle/laws/policies.htm#lfpcguid on July 20, 2009.

7Minnesota Pollution Control Agency. “Closed Landfill Program – Land Use Planning.” September 2008. Retrieved online from http://www.pca.state.mn.us/publications/c-clf1-02.pdf on August 11, 2009.

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